Articulation rate and speech-sound normalization failure.

Not all children with speech delay (SD) of unknown origin develop fully normal speech even with intervention. Many retain residual distortion errors into adolescence and ultimately into adulthood. The current study examined whether articulation rate distinguishes those children who retain residual errors from those who normalize. Two groups of speech-delayed children originally identified at preschool age were retested at age 9 years (the early follow-up group) and at age 12-16 years (the late follow-up group), respectively. No differences in articulation rate were observed at either test time in conversational speech between those children who continued to produce residual distortion errors (RE) compared to those children who had fully normalized speech (NSA). For the late follow-up group, children in the RE outcome group articulated speech at significantly slower rates than the children in the NSA outcome group in an embedded words task using both syllables per second and phones per second measures. Findings suggested that children with SD of unknown origin who fail to normalize may have relative speech-motor deficits and possibly deficits in language formulation skill. Alternatively, slower articulation rate in structured tasks may represent some sort of compensation for the continuing presence of speech-sound errors. Possible motivations for such compensation are discussed.